Process for nickel-cobalt separation



United States Patent O 3,514,282 PROCESS FOR NICKEL-COBALT SEPARATION Tunis L. Holmes, Deerfield, and Robert N. Moore, Des Plaines, Ill., assignors to Meta Chemical, Inc., Chicago, Ill., a corporation of Delaware No Drawing. Filed June 19, 1967, Ser. No. 647,243

Int. C1. C22]: 23/04 US. Cl. 75-82 6 Claims ABSTRACT OF THE DISCLOSURE A process for separation of nickel from cobalt found in mixtures and compounds containing both wherein same BACKGROUND OF INVENTION The resemblance of nickel and cobalt to each other is especially notable in appearance, melting points, densities, ionization potentials and other physical and chemical properties of the elements. The similarity in their chemical behavior is explained by the virtual identity of the electron configurations of their respective atoms. These resemblances and similarities of behavior characteristics have lead to the long-experienced obstacles to development of an economical method of separating and recovering them.

Existing commercial processes are characterized by complicated and expensive steps incident to electrolytic refining or hydrogen reduction in autoclave-s. These processes are further characterized by significant yield inefficiencies in that the residues contain substantially all of the cobalt contaminated with material amounts of nickel, the residues being unusable without significant further processing.

Many of the numerous suggested processes for separating nickel from cobalt entail expensive means of extraction. Some of these processes necessitate recycling of substantial portions of the material before commercially acceptable separation can be achieved.

The method of the present invention defines an improvide means for separating nickel from cobalt in mixtures and compounds containing both.

Accordingly, it is an object of the present invention to provide an improved process for separating nickel from cobalt in mixtures and compounds containing both.

Another object of the present invention is to provide an improved process for separating nickel from cobalt, wherein the separation is achieved through heating the mixtures and compounds to predetermined temperatures, thereby taking advantage of the discovered effects of the temperatures on the disparate solubility characteristics of the respective elements.

A further object of the present invention is to provide an improved process for so separating nickel from cobalt, which is inexpensive to carry-out, which characteristically assures commercially acceptable separation and which is readily adapted to continuous processing techniques.

Still another object of the present invention is to provide an improved process for so separating nickel from cobalt and for recovering both elements in substantially pure form.

The novel aspects of the present invention are set forth with particularity in the appended claims. However, other objects and advantages will become apparent from a reading of the detailed disclosure herein.

DESCRIPTION OF THE INVENTION The method of the present invention relates to a process for treating nickel-cobalt bearing mixtures and compounds, separating and recovering them in substantially pure form, the elements being separated as the result of the different solubility characteristics of the two brought about by subjecting them to predetermined temperatures.

In general, the process developed by us will effect the desired separation and recovery in most nickel-cobalt bearing mixtures and compounds. We have conducted numerous tests and development work on mixtures and compounds containing difiering ratios of the respective elements to determine the technique and process parameters.

The input nickel-cobalt bearing material is first heated in air to a temperature of about 1000 F. for a time sufficient to achieve maximum solubility for the nickel while rendering the cobalt insoluble to the maximum degree. The heated product is then treated with any suitable solvent, e.g., 1.0% (by volume) sulphuric acid, until the soluble nickel portion is dissolved.

The filtrate or soluble fraction will have a nickel/ cobalt ratio of /10 or higher, from which the cobalt can be separated and recovered by means of the hypochlorite technique long known to the art, leaving a solution of commercially pure nickel.

The insoluble fraction, which is much higher in cobalt than in nickel, is heated to 1300 F. for a time sufiicient to achieve maximum insolubility for the cobalt while rendering soluble the remaining undissolved nickel. Again, this product is treated with a suitable solvent for a time sufiicient to dissolve the nickel portion. The insoluble fraction is substantially pure cobalt.

The residual filtrate, containing both nickel and cobalt, can be economically recycled by precipitating the elements with soda ash and treating the resulting carbonate as described above.

It is to be noted that the process is adapted to separation and recovery from nickel-cobalt mixtures and compounds regardless of component ratios, except that if the ratio of nickel to cobalt is 90/10 or higher, the first step is omitted and the nickel-contaminated cobalt recovered from the hypochlorite step is recycled through the entire process.

EXAMPLES A significant amount of testing has been done to determine the variable characteristics of the process for the separation of nickel from cobalt as set forth herein. This testing was done with varying ratios of nickel to cobalt as starting materials to determine the ability to achieve separation of nickel from cobalt. It should be observed that in carrying out the process of the present invention different solvents may be utilized. In most of the examples set forth below sulphuric acid was used to dissolve the materials. However, other acids or solvents may be used and we specifically note that nitric acid or hydrochloric acid can be employed with equally good results.

EXAMPLE I The starting or input material for this example was a synthetic sulfate containing a nickel to cobalt ratio of 50/50. The material was dissolved in water and the elements precipitated as carbonates using soda ash at a hydrogen ion concentration of approximately 8.0. The resulting carbonate was dried, crushed and ground until it passed through a twenty-mesh screen. The screened material was heated in air to approximately 450 F. for eight hours. The heated material then was cooled and subsequently treated with .75 (by volume) sulphuric acid at approximately 200 F. and stirred for six hours. It should be noted that varying acids and acid concentrations may be employed in carrying out this process. The acid treated solution then was cooled and filtered to separate the soluble portion from the insoluble portion. The filtrate contained a nickel to cobalt ratio of 52/48 while the insoluble portion contained a nickel to cobalt ratio of 23/77.

EXAMPLE II The input material for this example was the same as that noted for Example I and the processing steps were the same up to the heating of the ground, dried carbonate. In this example the material was heated to approximately 660 F. for about 13 hours. The material then was cooled and treated with .75% (by volume) sulphuric acid and stirred for four hours. The acid treated solution then was cooled and filtered and it was found that the nickel to cobalt ratio of the filtrate was 60/40 while the nickel to cobalt ratio of the insoluble portion was 24/76.

EXAMPLE III The input material of this example was the same as that noted above for Example I and the material was processed in the same manner up to the step of heating the ground and screened material. In this example the material was heated to approximately 800 F. for about fifty hours. The material then was cooled and treated with .75% (by volume) sulphuric acid at a temperature of about 200 F. and stirred for about five hours. The acid treated material then was cooled and filtered and it was found that the filtrate had a nickel to cobalt ratio of 76/24 while the insoluble portion had a nickel to cobalt ratio of 22/78.

EXAMPLE IV The input material of this example was the same as that set forth in Example I and the material was treated in the same manner as that set forth in Example I through the screening step. The material then was heated to 1000" F. for about forty-five hours. The material then was cooled and treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for about six hours. The acid treated solution was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 93/7 while the insoluble portion contained a nickel to cobalt ratio of 9/91.

EXAMPLE V .75% (by volume) sulphuric acid at a temperature of' 200 F. and stirred for about five hours. The solution was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 75/25 while the insoluble portion contained a nickel to cobalt ratio of EXAMPLE VI The input material of this example was the same as that set forth in Example I and the processing was the same through the screening step. The material then was heated to approximately 1300 F. for about thirty hours. The heated material was cooled and treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for twenty-two hours. The solution was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 53/47 while the insoluble portion contained a nickel to cobalt ratio of 100.

EXAMPLE VII The input material of this example was substantially the same as that set forth in Example I and the processing was the same through the screening step. The material then was heated to approximately 1500 F. for twentyfour hours. The material was cooled and then treated with .75% (by volume) sulphuric acid at a temperature of about 200 F. and stirred for nine hours. The solution was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 60/40 while the insoluble portion contained a nickel to cobalt ratio of 46/54.

EXAMPLE VIII The input material of this example was a synthetic sulfate having a nickel to cobalt ratio of approximately 10/90. The material was dissolved in water and the elements precipitated as carbonates using soda ash at a hydrogen ion concentration of approximately 8.0. The carbonate was dried, crushed and ground until it passed through a twenty-mesh screen. The screened material then was heated to approximately 1000 F. for twenty hours. The as-heated material was cooled and then treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for about six hours. The solution then was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 34/66 while the insoluble portion contained a nickel to cobalt ratio of 12/88.

EXAMPLE IX The material of Example IX was substantially the same as that of Example VIII and the processing the same through the screening step. The screened material then was heated to about 1100" F. for about twenty-four hours. The as-heated material was then cooled and treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for about six hours. The solution then was coo-led and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 61/39 while the insoluble portion contained a nickel to cobalt ratio of 7/93.

EXAMPLE X The input material of this example was substantially the same as that set forth in Example VIII and the processing the same through the screening step. The screened material then was heated to approximately 1200 F. for about thirty hours. The as-heated material was cooled and treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for six hours. The acid treated material then was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 47/53 while the insoluble portion contained a nickel to cobalt ratio of 8/ 92.

EXAMPLE XI The input material of this example was substantially the same as that set forth in Example VIII and the processing was the same through the screening step. The screened material then was heated to a temperature of about 1300 F. for about twelve hours. The as-heated material was cooled and treated with nitric acid at a temperature of about 200 F. and stirred for about eighteen hours. The solution then was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of about 14/86 while the insoluble portion contained a nickel to cobalt ratio of 2/98.

EXAMPLE XII The input material of this example was the same as that set forth in Example VIII and the processing was the same through the screening step. The screened mate rial was heated in air to a temperature of about 1300- F. for approximately twelve hours. The as-heated material was then cooled and treated with .75 (by volume) sulphuric acid at a temperature of about 200 F. and stirred for about eighteen hours. The solution was cooled and filtered and it was found that the filtrate contained a nickel to cobalt ratio of 17/83 while the insoluble portion contained a nickel to cobalt ratio of 3/97.

In the claims the term solvent is used to designate any suitable material for placing the designated material into solution.

While we have specifically described differing processing sequences for carrying out the separation of nickel from cobalt as set forth herein, it will be understood that numerous alternatives may be used to obtain the advantages of this process of the separation of nickel from cobalt and it is intended by the following claims to cover all such modifications and alternatives as fall within their true spirit and scope.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An improved method for the separation of nickel from cobalt from a material containing both nickel carbonate and cobalt carbonate, the method including the steps of:

heating the material to a temperature in the range of 800 F. to 1500 F. for a period of time sufficient to affect the solubility characteristics of the material to achieve maximum solubility for the nickel portion while rendering the cobalt portion insoluble;

dissolving the soluble portion of the as heated material in. a suitable solvent:

separating the soluble portion from the insoluble portion whereby the soluble portion contains a high ratio of nickel to cobalt and the insoluble portion contains a high ratio of cobalt to nickel.

2. The process of claim 1 wherein the material is heated up to fifty hours.

3. The method of claim 1 wherein the soluble portion of the as-heated material is dissolved in 1%, by volume, sulphuric acid at about 200 F.

4. The method of claim 1 wherein the material is heated to a temperature of about 100 F. for approximately ten hours and treated with a suitable solvent to dissolve the nickel portion of the as-heated material.

5. The method of claim 1 wherein the material is heated to about 1300 F. for approximately twelve hours.

6. The method of claim 1 wherein the solvent may be selected from the group consisting of: sulphuric acid, nitric acid and hydrochloric acid.

References Cited UNITED STATES PATENTS 2,400,115 5/1946 Hills et a1 75-82 2,508,427 5/1950 Shelton 751 19 2,757,077 7/1956 Lewis et a1 75-119 L. DEWAYNE RUTLEDGE, Primary Examiner "I". R. FRYE, Assistant Examiner US. or. xn. 75-401, 119 

